Boeing on Tuesday confirmed the signing of a memorandum of understanding (MOA) with state-controlled Iran Air for an unspecified number of new airliners. In a written statement, the U.S. airframer gave no details about the provisional deal, which had been announced earlier the same day by Iran’s transport minister Abbas Akhoundi speaking on Iranian television. Iran Air has previously indicated that it wants to refresh its aging fleet with a mix of approximately 100 new 737s, 777s and 787s.

The statement from Boeing acknowledged that conclusion of the sale remains very much in the hands of the U.S. government. Still unresolved is whether export credit support will be available from the U.S. ExIm Bank, which remains mired in indecision due to the fact that it still does not have a fully quorate board. Last year, the bank was mired by political rancor with Republicans in Congress obstructing reauthorization funding for the bank and then stalling over the approval of new board members.

Boeing did not refer to these difficulties in its statement and said that it would provide no further details. “Boeing negotiated the MOA under authorizations from the U.S. government following a determination that Iran had met its obligations under the nuclear accord reached last summer,” the company explained. “Boeing will continue to follow the lead of the U.S. government with regards to working with Iran’s airlines, and any and all contracts with Iran’s airlines will be contingent on U.S. government approval.”

Following the lifting of sanctions against Iran, Europe’s Airbus quickly signed a $27 billion deal for around 118 of its airliners, and this was supplemented by a $1 billion agreement for 20 ATR72-600 regional aircraft. However, these agreements also remain contingent on U.S. government approval as the aircraft all have significant U.S. content.